Harris–Benedict equation

The Harris–Benedict equation (also called the Harris-Benedict principle) is a method used to estimate an individual's basal metabolic rate (BMR).

The estimated BMR value may be multiplied by a number that corresponds to the individual's activity level; the resulting number is the approximate daily kilocalorie intake to maintain current body weight.

The Harris–Benedict equation may be used to assist weight loss — by reducing kilocalorie intake number below the estimated maintenance intake of the equation.[citation needed]

While the original paper does not attempt to translate BMR into total energy expenditure (TEE), a BMR result may be multiplied by a factor that approximates an individual's physical activity level (PAL) to estimate their TEE. The following table enables approximation of an individual's daily TEE based on some example lifestyles.[5]

As the BMR equations do not attempt to take into account body composition, identical results can be calculated for a very muscular person, and a very fat person, who are both the same height, weight, age and gender. As muscle and fat require differing amounts of calories to maintain, the TEE estimates will not be accurate for such cases.

The paper behind the latest update (Mifflin et al) to the BMR formula states all participants in their study fall within the 'normal' and 'overweight' body mass index (BMI) categories, and so the results also do not necessarily apply to those in the 'underweight' or 'obese' BMI categories.